The present invention relates to a rotary device, such as a fluid pump or motor, and a method by which it is assembled.
The end plates and cam rings used in vane type pumps and motors are typically unidirectional. As such, different end plates must be provided for clockwise or counterclockwise rotation. The profile of the working surface in the cam ring is typically an inverted mirror image about a center plane through the minor diameter of the cam ring.
The orientation of the end plates and the cam ring in a pump or motor is critical to proper and efficient operation. Two methods of aligning the end plates with the cam ring and pump or motor body have been previously been used. The first of these two methods is to use two alignment pins spaced 180.degree. apart. These pins pass through holes in the body, lower or wear end plate, cam ring, and top or pressure end plate. The clearance between the holes and pins is held to a slip fit and the angular location of the holes is also closely held. The second method is to use a single alignment pin passing through the assembly. The clearance between the outer diameter of the plates and the cam ring is held very close to the inside diameter of the pump or motor body.
Both of the aforementioned methods accurately locate and position the end plates, cam ring, and pump body. Neither of these alignment methods prevent accidental misassembly of the pump or motor. It is possible with both alignment methods to install the end plates and/or cam ring out of position. Installing the end plates out of position will cause improper operation.
To save wasted effort due to improper assembly both in production and during repair operations in the field, it is desirable to design an end plate alignment system such that is impossible to assemble the pump or motor with the end plates and cam ring incorrectly aligned.